The invention is directed to scratch resistant, antistatic sound and picture carriers made of synthetic resin, especially sound and video discs which are provided with a metallic surface layer and a process for their production.
Sound and picture carriers made of synthetic resins, such as sound discs, video discs, or other mechanically contacted information carriers, relatively quickly after a limited frequency of play-back lose their quality of reproduction through mechanical wear of the carrier material and through electrostatically attracted dust. Besides the electrostatic charges lead to impairing the quality of reproduction.
It is known to make sound discs scratch resistant and antistatic by coating with gold coatings. For this purpose the carrier disc, for example made of polyvinyl chloride, is first coated chemically with an electrically conductive nickel layer having a thickness of 2-3.mu. and this is subsequently gold plated electrolytically with a layer thickness of about 5.mu.. Such sound discs indeed no longer can be played back without objection and have a low sound quality.
Furthermore, it is known to deposit on sound discs in a high vacuum a thin layer of gold having a thickness of about 0.5.mu.. Such sound discs have a very good optical effect and also permit play-back. However, the adhesive strength of the gold layer to the synthetic resin carrier is so low that the gold coating after a few play-back cycles is abraded off.
It is true that by applying a base lacquer layer to the carrier surface before the gold coating the adhesive strength of the gold layer can be improved, however, the lacquer layer adds to the sound or picture tracks so that such discs can no longer be played back and only serve decorative purposes. The decorative purpose is prominent also in all other previously known sound and video discs provided with a metal layer. These are little suited for play-backs.
Therefore, it was the problem of the present invention to provide scratch resistant and antistatic sound and picture carrier made of synthetic resin, especially sound and video discs, which are provided with a metal surface, which not only has a decorative appearance but also as frequently as desired permits playing back with constant sound or picture quality.